Telephone system



May 5, 1941- w. H. T. HoLDEN ETAL 2,241,031

vTELEPHONE SYSTEM Filed Jan. 25, 1940 4 SheBtSSheet 1 mit N .um .um m. ,a

ATToR/VEV V W H. HOL DEN FRANC/s A. HUBBARD /NVE N TORS @1D-Mi @My s, 1941.

` w. H. T. HOLDEN ETAL TELEPHONE SYSTEM Fneduan. 25, 1940 4 Sheets-Sheet 2 w H. 7.' HOLDEN /NVENTORS FRANC/s A. HUBBARD By @aw May 6, 1941- w. H. T. HOLDEN Erm. 2,241,031

TELEPHONE SYSTEM Filed Jan. 23, 1940 4 Sheets-Sheet 3 u w s a J IIIVAV s; 5 m IMI-il' l,l I o,

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By M

ATTORNEY TELEPHONE SYSTEM W H r HOLDEN NVEWORSFRANC/s A. HUBBARD By @am A TTORNE V Patented May 6, 1941 I TELEPHONE SYSTEM William H. 'l'. Holden. Long Island City, N. Y., and

Francis A. Hubbard. Maplewood, N. J., assign to Bell Telephone laboratories, Incorporated, New York, N. Y., a corporation of New York Application January z3, 1940, serial No. 315,14z

(ci. 11a-1s) 1l Claims.

This invention relates to telephone systems and has for its object to improve such systems by the use of novel equipment.

More specifically, the invention contemplates the identification of desired pieces of equipment by establishing a eld of lights and scanning the field by means of an electric eye."

'I'he invention may be embodied, for example, in means for selecting an idle trunklby a marker in the cross-bar system. Lamps corresponding to all the trunks outgoing from an oiilce are arranged in a bank, with means for lighting the lamps corresponding to idle trunks. An image of this bank is focussed kon the screen of a cathode ray tube, known as an. iconoscope, which scans the bank, and signals when an idle trunk is reached. 'Y

A further feature of, the invention comprises t ning is to take place, and only those lamps will be lighted which belong to the group of trunks leading to the wanted ofilce.

These andother features of the egntempiats invention t the type in which the present invention may be employed.

In such a system a calling subscriber, on initiatlng a call, is connected over primary and secondary line switches to a district junctor circuit and through primary and secondary sender selectors to a sender. 'Ihe subscriber then dials the wanted number which is recorded in the sender. When the sender has received the digits identifying the oflice in which the wantedline is located, the sender associates itself with an idle marker `through a marker connector and transmits these digits to the marker. The marker translates these digits vand operates a route relay which identifies the trunks leading to the wanted oillce.

- In the Carpenter patent, the route relay causes the association of the identified trunks in groups A with a set of test relays, in order to find an idle f one, after which the channels connecting the dise tion, the lamps may be lighted only -when scanf' tri'cty junctor `with the selected trunk are tested and idle set of district and oiiice selectors are operated; When this connection is established, the outgoing trunk is marked with ground by the districtijunctor. two scanning,

L According tothe present arrangement, a lamp 11SVY Drovided'foreach outgoing trunk in the lamp ILI0 .The trunks outgoing to a particular joillc'e arejarran'ged in'a single group in the bank, irrspective'of the positions of the trunks on the trunk-frame. The lamps are all connected to ground-atene side and to battery on the other be more apparent from a yconsideration of the ensuing *description* .in. connection with 'the drawings, in which:

Fig. 1 shows, in diagrammatic form,"v a telephone connection between a calling line and an outgoing trunk, a sender and a marker, as well as the lamp panel common to the trunks, and the scanning tubes for a plurality of markers;

Fig. 2 shows the route relays and their crossconnections;

Fig. 3 shows the radial beam tubes which identify the trunk;

Fig. 4 shows the radial beam tubes which control the iconoscope amplifier; and

Fig. 5 shows the manner in which Figs. 1 to 4 are to be arranged.

Certain aspects of this disclosure form the basis for the copending application of 0.. B.Blackwell, Serial No., 315,149, filed January 23, 1940.

Reference is here made to Patent No. 2,235,803, granted March 18, 1941, to W. W. Carpenter, for

a detailed Vdescription of a telephone System ofv and thereforeV are normally lighted. When a trunk becomes-busy, the busy ground 'lamp and extinguishes it.

.'When the subscriber at substation |05 is connected to district junctor |06 and sender |01, he dials the wanted designation. The sender i01 calls in a marker and transfers the code digits to the marker registers |08. These digits are translated by means indicated as translator |09 and cause the operation of one of the route relays 20| to 20|, for example relay 204. This relay identifies the ofllce in which the wanted line is located and thereby the group oi' trunks to be used.

Each marker has an iconoscope such as iconoscope I I i, provided with a screen I I3 made up of photoelectric elements corresponding in number to the number of lamps, and these iconoscopes are arranged before the lamp bank so that the image of the lamp bank may be focussed by suitable means, indicated by lensw H2, on the screen H3. In this way, one lamp bank serves all of the markers of the ofllce. The iconoscopes of four markers are indicated in Fig. l.

shunts the 'Whenever the of electrons in the iconoscope traverses an illuminated spot on the screen there will be an impulse of voltage on the iconoscope output lead |20.

Assuming that there are twenty-live hundred lamps and twenty-live hundred elements, the

frequency of one sweep will be one-fiftieth Qf the other. Two interlocked oscillators (not shown) may be used to supply-the sweep frequencies.y

The output of the iconoscope is fedto amplifier H0.

In order tolimit the iconoscope amplifier to indications on only a particular trunk group, the output therefrom is blocked except when the beam is sweeping over those spots in the screen receiving light from lamps of a particular trunk group. To this end conductors I|4 and I|5 are connected to the control circuit 200 which applies either positive or negative potential to them, under the control of the route relays 20|, etc., and the timing circuit of Fig. 4. When either conductor ||4 or conductor H5 is negative, the output of the ampliiier is blocked, while when both conductors are positive, output from the ampliiier will be possible.

'I'he blocking of the output of the amplier is controlled by two radial beam tubes 450 and 45|, which provide a low voltage, high current beam. Tubes of this type are disclosed in Patent No. 2,217,774, granted Oct. l5, 1940, to A. M. Skellett. 'I'he beams of the tubes 450 and 45| are rotated by a revolving magnetic eld, as described in the Skellett patent, produced from a two-phase alternating current supply. Tube 45| operates at high speed and its ileld supply, indicated at 452 but not shown in detail, is arranged so that vone of its phases Ais in synchronism, with the horizontal sweep supply of the iconoscope lli. Tube 450 operates from a source 453 similar to source 452 but having one of its phases in synchronism with the vertical sweep supply oi the iconoscope lill. Each tube has fifty anodes arranged to receive'the beam, the beam in tube 45| traversing the entire fty anodes while that in tube 450 traverses a single anode. A resistance 454, 455, etc., and 459, 450, etc., is connected between each of the anodes of tubes 450 and 45| and ground, and in parallel therewith a conductor leads from each anode to the fifty terminals on each of the blocks 2|0 and 2| I. These two terminal blocks are crossconnected to a plurality of groups of four terminals each on a block 2|2. Only four groups of terminals of four each, corresponding to the four route relays to 204 are shown, but it is to be understood that there will be as many fourterminal groups and route relays as there are separate trunk group destinations to be reached by the decoder-marker.

It is evident that with twenty-ve hundred trunks, represented by twenty-tive hundred lamps in a bank fty lamps wide and fty lamps high, any trunk may be identified by two numbers, each of which may have any value from one to fifty and the two groups of fifty terminals of blocks 2|0 and 2li, corresponding as they do to the positions of the beams in the tubes 45| and 45| and therefore to the position of the scanning beam in the iconoscope, also correspond to the coordinate numbers of the trunks.

Specifically, terminal 2|! on the block 2|2, which may be called the group start terminal. is cross-connected to terminal No. l on block 2I0, while terminal 2|0, which may be identied as the trunk group terminal, is cross-connected to terminal No. l of block 2| I. If we assume that this group consists of ilfty trunks, the group end terminal 2|1 will be connected to terminal No. 50 of block 2|0. It now, route relay 204 is operated, conductor ||4 is connected to terminal 2|! and receives a positive potential from the anode circuit of tube 450 so long as the electron beam in the tube rests on anode No. l.

Terminal 2|0 is connected by relay 204 to resistance 225 in the input circuit of the thyratron 224. Therefore, as soon as the beam in tube 45| strikes the No. 1 anode. a positive pulse will be sent through resistance 225, operating thyra tron 224 through condenser 225, extinguishing any arc which may exist in tube 22| by means of the commutating condenser 223 and applying positive bias to conductor ||5. There is now positive bias on both conductors I4 and ||5, unblocking the iconoscope amplifier. But 'tube 224 was operated by the arrival of the beam in tube 45| on anode No. 1 and conductor ||4 was made positive by the beam of tube 450 resting on No. 1 anode in that tube. Owing to the synchronism between supplies 452 and 453 and the iconoscope sweep sources, however,.this occurs when the iconoscope spot just arrives at the ilrst element in the first row on which the image of lamp Ill which is the ilrst lamp in the ilrst horizontal row of lamp panel |00 is focussed. There will thus be output from the iconoscope ampliiler for every lamp lighted in this row, beginning with the first.

y supposing iirst that no lamps are found lighted, corresponding to an all-trunks-busy condiditlon, nothing will happen until the beam in tube 45| reaches anode No. 50, which was connected over terminal 2|1 and the outer right contact of route relay 204 to ground through resistance 22|. When the beam in tube 45| reaches anode No. 50, a positive impulse will then pass over terminal 2|1 through condenser 222 to the grid of thyratron 22|, causing an arc to strike therein, and extinguishing the arc previously struck in tube 224 by means of condenser 223. This removes positive bias from conductor ||5 and again blocks the output of the iconoscope amplifier. As no trunk was found, route relay 204 remains operated, relay 228 operates in the output of tube 22| and closes a circuit from ground `at the inner right contact of relay 204, conductor 229. back contact of relay 302, conductor 3| 5, front contact of relay 228, conductor 230 and thence to the trunks-busy relay 23| which brings about the transmission of an overilow signal to the calling subscriber. Relay 23| would be timed in operating to prevent its premature operation.

For route relay 204, terminal 232 has no function. To understand the purpose of this terminal, suppose that the second trunk group, to which route relay 203 appertains, begins with the iirst trunk of the second row and ends with the thirty-eighth trunk of that row and that the third trunk group, to which route relay 202 appertains, begins with the thirty-ninth trunk of the second row and ends with the first trunk of the third row. In the case of this third group group stm terminal m is connected to tenml nal 33 oi' block 2li, trunk group terminal 2|0 .is connected to terminal No. 2 of block 2|| and group end: terminal 2|3 is connected to terminal No. 1 of block 2| 0. Terminal 2|4, whichis multipled to terminal 2|| over the contacts of relay 202. is connected to terminal No. 3 of block which are normally so biased as to suppress the beam, 'I'he iield coils of tubes 300 and 30| are excited from the same Sources 453 and 452 as are the tubes 050 and 45|, respectively. Therefore., 4the beams in tubes 300 and 30|, when they exist, agree exactly in position with those in tubes 450 and 45|, respectively. The output of the iconoscope amplier is fed tothe control grids of tubes 300 and 30| by means of transformer 301, so that when the iconoscope beam strikes an illuminated screen element, and the ampliiler is unblocked, the impulse to the grids 303 and 304 causes the beams of the tubes 300 and 30| to flash to the anodes of these tubes and they will encounter the anodes having the same positions in tubes 300 and 30| as those in tubes 450 and 45| on which the beams of the latter tubes are resting. This ilash of the beams will cause one of the fty cold cathode tubes 308, etc., associated -with tube 300 -to break domi and also one of the ilfty tubes 358, etc., associated with tube 30| to break down. Since the upper Winding of relay 302 is included .in the output of the cold cathode tubes, it willoperate and open the circuit of trunks-busy relay 23|. At the same time, the impulse generated in the lower winding of relay 302 will cause tube 22| to operate, extinguishing the arc in tube 224 and again disabling the iconoscope amplifier so that only one cold cathode tube operates in each of the groups associated with tubes 300 and 30|.

The cathode circuits of tubes 308, 309, 358, 359,

etc. pass through the windings of a cross coil switch 350 of the type described and claimed in Patent No, 2,187,115 to W. B. Ellwood and W. H. T. Holden, granted January 16, 1940. This switch has fty vertical coils 328, 329, etc., and tlfty horizontal coils 368, 369, etc., with a single pair of contact springs at each cross-point, whereby it includes twenty-ve hundred contacts. One spring of all of these pairs is grounded, so that the operation of the switch connects ground to the particular conductor corresponding to the desired trunk. This can be utilized to connect the trunk to the district junctor. Such an arrangement suitably modied could be used in any type of switching system. l

As an alternative to the blocking of the iconoscope amplifier, to limit the scanning to the group of trunks desired, a route relay like relay might, as indicated, close circuits for only those lamps included in the group, thereby eliminating tubes 450 and 45| and the cross-connection blocks and tubes of Fig. 2. However, the time for holding the marker is so short that probably this would be satisfactory only if noniilamentary lamps were used.

The advantages of this arrangement lie both in the saving of equipment and in fthe saving of time, particularly where large trunk groups are involved.

What is claimed is:

1. In a telephone system, a plurality of circuits, a bank of lamps containing onelamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a cathode ray tube, means to focus an image of said bank of lamps on the screen of said tube, means to scan said screen, means responsive to the cathode ray beam striking an illuminated point on `the screen to stop the scanning operation and to identify the corresponding circuit, and means to render said last-mentioned means responsive during a predetermined limited portion of said scannin operation.

2. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a cathode ray tube, means tov focus an image of said bank of lamps on the screen of said tube, means to scan said screen,

an amplier in the output of said tube, means in the output of said amplilier responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and toidentify the corresponding circuit, and means to block said amplier while scanning undesired portions of said screen.

3.` In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuit, a cathode ray tube, means to focus an image of said bank of lamps on the screen of said tube, means to scan said screen, means responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to identify the corresponding circuit, an amplifier between said tube and said responsive means, means driven in synchronism with the scanning beam of said tube, and means controlled by said last-mentioned means to block said amplifier while scanning undesired portions of said screen.

4. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a cathode ray tube, means to focus an image of said bank of lamps on the screen of said tube, means to scan said screen, means responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation .and to identify the corresponding circuit, an amplifier between said tube and said responsive means,

cathode ray means driven in synchronism with I the scanning beam of said tube, and means con trolled by said last-mentioned means to block said ampliiier while scanning undesired portions of said screen.

5. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a selection control device comprising a cathode ray tuibe, means to focus an image of said bank of lamps on the screen of said tube, means to scan said screen. means in said selection control device to identify a wanted group of circuits, an amplifier, means controlled by said ampliiier responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to mark the corresponding circuit, and means under the control of said identifying means to render said amplier eective only while said tube scans the corresponding portion of said image.

6. In a telephone system. a plurality of circuits,a bank of lamps containing one lamp for each circuit, means to control the lighting oi' said lamps in accordance with the busy or idle condition of said circuits, a cathode ray tube. means to focus an image of said bank of lamps on the screen of said tube, means to scan said screen, means responsive to the cathode'ray beam striking an illuminated point on the screen to stop the scanning operation and to identify the corresponding circuit, an amplifier between said tube and said responsive means, a pair of radial beam cathode ray tubes driven in synchronism with the vertical and horizontal l sweeps oi' said rst cathode ray tube, and means -under the Joint control of said radial beam cathode ray tubes for blocking said amplifier while scanning undesired portions of said screen. '7. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of saidlamps in accordance with the busy or idle condition of said circuits, a cathode ray tube, means to focus an image in said bank of lamps on the screen of said tube, means to scan said screen, means responsive tothe cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to identify the corresponding circuit, an ampliiier between said tube and said responsive means, a pair of radial beam cathode ray tubes driven insynchronism with the vertical and horizontal sweeps o1' said flrst cathode ray tube, means for normally blocking said amplier and means under the joint control of said radial beam cathode ray tubes for rendering said blocking means ineffective while the desired part of said screen is being scanned.

8. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a selection control device comprising a cathode ray tube, means to.

focus an image of said bank of lamps on the screen of said tube, means to scan said screen, means in said selection control device to identify, a wanted group of circuits, an amplifier, means controlled by said ampliiier responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to mark the corresponding circuit. cathode ray means driven in synchronism with the scanning beam of said tube, and means under the joint control oi' said cathode ray means and said identifying means to render said amplier eiective only while said tube scans the corresponding portion of said image.

`9. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in laccordance with the busy or idle condition of said circuits, a selection control device comprising a cathode ray tube, means to focus an image of said bank otvlamps on the screen of said-l tube, means to scan said screen, means in said selection control device to identii'y a wanted group of circuits, an ampliier, means controlled by said amplier responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to mark the corresponding circuit, a

pair of radial beam cathode ray tubes driven in,

Isynchronism with the vertical and horizontal sweeps of said ilrst cathode ray tube, and means under the Joint control of said radial beam cathode ray tubes and said identifying means to render said amplifier eilective only while said rst tube scans the corresponding portion oi said image.

10. In a telephone system, a plurality of circuits, a bank of lamps containing one lamp ior each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a selection control device comprising a cathode ray tube, means to focus an image or said bank of lamps on the screen of said tube, means to scan said screen, means in said selection control device to identify a wanted group of circuits, an amplifier, means controlled by said amplifier responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to mark the corresponding circuit, means for normally blocking said amplifier, means under the joint control of said radial beam cathode ray tubes for rendering said blocking means ineffective while the desired part oi' the screen is being scanned and means under the control of said identifying means for associating said ,radial beam cathode ray tubes with.l said amplier.

11. In a telephone system, a plurality of' circuits, a bank of lamps containing one lamp for each circuit, means to control the lighting of said lamps in accordance with the busy or idle condition of said circuits, a selection control device comprising a cathode ray tube, means to focus an image of said bank o1' lamps on the screen of said tube, means to scan said screen, a plurality of route relays, means in said selection control device to operate one of said relays individual to a wanted group of circuits, an ampiier, means controlled by said amplifier, responsive to the cathode ray beam striking an illuminated point on the screen to stop the scanning operation and to mark the corresponding circuit, means for normally blocking said amplifier, means under the joint control of said radial beam cathode ray tubes for rendering said blocking means ineiective While the desired part of the screen is being scanned, and means under the control of said relay for associating said radial beam cathode ray tube with said amplier.

. WILLIAM H. T. HOLDEN.

FRANCIS A. HUBBARD. 

